Knit spacer fabric for motor-vehicle interior

ABSTRACT

The invention relates to spacer fabric comprising a first and a second generally planar knitted layer ( 1, 2 ) that are attached to each other by spacer threads ( 3 ), wherein the spacer threads ( 3 ) in the first knitted layer ( 1 ) form stitches by an intertwining of threads. According to the invention, the spacer threads ( 3 ) on the second generally planar knitted layer ( 2 ) do not form stitches, wherein the spacer threads ( 3 ) are interlaced there only as an inlay. The object of the invention is also a motor vehicle interior furnishing item that includes this spacer fabric as cover material. The spacer fabric is disposed in such a way that the second generally planar knitted layer ( 2 ) forms the exposed surface.

The invention relates to a spacer fabric comprising a first and secondgenerally planar knitted layer that are attached to each other by spacerthreads.

Generic spacer fabrics have been disclosed, for example, in DE 199 03070 and DE 90 16 062. The known spacer fabrics are employed as soft,elastic layers, and layers that provide air circulation, in mattresses,upholstered furniture, items of clothing, or shoes. In addition, spacerfabrics find widespread use in the automotive field, such as, forexample, for climate-controlled seats and seat covers where the spacerfabrics allow for effective adaptation to contours due to their superiorrecovery properties. For example, spacer fabrics are thus analternative, for example, to foam padding where a wear-resistant coverlayer of leather or cloth is typically provided.

In the known spacer fabrics, the spacer threads are interlaced in thesame way in both knitted layers, specifically, such that spacer threadsin the first knitted layer and in the second knitted layer form stitchesdue to the intertwining of threads. The spacer threads here areintertwined with each other and/or with the threads of the knittedlayers. The formation of stitches in the knitted layers enables thespacer threads to be strongly interlaced and aligned, thereby providingthe requisite compressive strength.

Despite the fact that spacer fabrics have proven quite successful inpractical use, there remains a need to enhance their resistance tomechanical stresses. The known spacer fabrics, in particular, entail thedanger that individual threads can be pulled out under mechanicalstress, thereby degrading the spacer fabrics both in terms of appearanceand functionality. This danger exists, in particular, whenever thespacer fabrics are exposed to pointed objects or even hook-and-loopfasteners that are often used in items of clothing.

For practical applications, padding materials undergo hook-and-loopfastener tests in which the sensitivity of padding materials are testedby a procedure approximating real use for wear and tear caused byhook-and-loop fasteners. Based on DIN EN ISO 12947-1, the GermanAutomotive Industry Association (VDA) has issued Test Specification VDA230-210 of December 2008. The test sample is subjected to appliedstresses by a hook strip, type 751, after which an assessment is made byvisual inspection and a grade is given based on five grade levels. Nochanges to the surface results in a score of grade 5, whereas completedestruction of the surface and the structure is assessed with a gradeof 1. Based on this referenced test specification, the goal is a gradeof 5 for a padding material that is suitable for long-term use in amotor vehicle, and this goal is difficult to achieve using known spacerfabrics, with the result that the known designs of vehicle seats arealways provided with an additional cover layer such as one composed, forexample, of cloth, leather, or artificial leather.

In light of the above, the object of this invention is to provide aspacer fabric that has enhanced resistance to wear from mechanicalstresses. In particular, the object is to provide a spacer fabric thatcan also be employed as a cover layer for a motor vehicle interior wherethis spacer fabric does not structurally degrade when used in the motorvehicle.

Based on a spacer fabric having the above-described features, the objectof the invention is attained in that the spacer threads do not formstitches on the second generally planar knitted layer and are onlyinterlaced there as an inlay. What is understood by this within thescope of the invention is that the spacer threads are held on the secondknitted layer by at least one associated thread without thereby forminga stitch by intertwining. The spacer threads are thus threaded throughin each case on at least one thread of the second knitted layer.

The second generally planar knitted layer in the spacer fabric accordingto the invention is provided as the exterior wear layer that is exposedto mechanical stresses, for example, hook-and-loop fasteners. The factthat the spacer threads are interlaced only as an inlay prevents asituation where these threads run along the exposed surface of thesecond knitted layer, and can thereby be caught by hook-and-loop hooksor other pointed objects and pulled out. Since the spacer threads areinterlaced only as an inlay, these threads can run along the inside ofthe second knitted layer with the result that the threads of the secondknitted layer essentially cover and thus protect the spacer threads.

An additional advantage to be considered is the fact that the spacerthreads in the described embodiment are also not visible on the exposedsurface of the second knitted layer. One aspect that must be consideredhere is that different thread types are typically used for a threadsystem of the second knitted layer on the one side and for the spacerthreads on the other side. As a result, the spacer threads often aremonofilaments so as to achieve a high compressive strength, whereasmultifilaments are preferably used for the cover layers. Within thescope of the invention, multifilament flat yarn is, in particular,well-suited for the second generally planar knitted layer, as such yarnthus does not swell out and accordingly has no texture.

In terms of the different described thread types for the secondgenerally planar knitted layer and for the spacer threads, it is notpossible to easily match these precisely for color. In addition to thecolor per se, another visual effect is also achieved. Since the spacerthreads according to the invention are interlaced only on the inside asan inlay on the second generally planar knitted layer, these threads arenot visible and cannot result in visual variation compared with thethreads of the second knitted layer.

It is of critical importance for the invention that the spacer threadsin the first knitted layer on the one hand and in the second knittedlayer on the other hand are interlaced differently. Since the spacerthreads in the first knitted layer form stitches due to threadintertwining either with each other and/or with the threads of the firstknitted layers, it is possible to achieve superior resistance under loadfor the spacer threads. The spacer threads here preferably form pileloops between the knitted layers, which loops each have loop feetcreated by stitches on the first knitted layer, and a loop head betweenthe pile loops, the pile loops on the loop head being held on the secondknitted layer.

The second knitted layer according to the invention can have a knitpattern comprising a perforated structure. This perforated structure isboth visually attractive and is also especially well suited fordissipating moisture and water vapor. In order, however, to ensure thatrelatively large particles of dirt or the like cannot penetrate into thespacer fabric, according to a preferred development of the inventionholes of the perforated structure on the inside of the second knittedlayer are covered by separate threads, in particular, by weft threadsthat run perpendicular to the knit direction. The shape of the holesaccording to the invention can vary. They can be round, oval, rhombic,or roughly rectangular.

Since the perforated structure can be generated with high uniformity,these weft threads can be matched in terms of color to the thread systemof the second generally planar knitted layer, or can also optionally beof contrasting color. A color contrast provides an especially easy wayto produce an attractive and vivid design.

If the spacer fabric has a perforated structure, a preferred developmentof the invention provides an approach wherein the second knitted layerhas a first stitch-forming and perforated-structure-generating threadsystem plus a second stitch-forming thread system, where starting fromthe exposed surface of the second knitted layer the stitches formed bythe first thread system are on the stitches formed by the second threadsystem and the spacer threads are held on the second knitted layer onlyby the second thread system. Providing a first thread system and asecond thread system enables the above-described advantages to befurther reinforced. The stitches lying on the outer surface of the firstthread system create optimal protection for the spacer threads that areunderneath on the stitches of the second thread system.

As has already been described above, the spacer threads are preferablymonofilaments, while the knitted layers can be composed both ofmonofilament threads and also multifilament threads, multifilamentthreads allowing a finer, more uniform surface structure to be produced.Especially well-suited are threads composed of polyester, where theespecially preferred approach is for both knitted layers and the spacerthreads to be entirely composed of polyester threads, thereby alsoenabling the spacer fabrics to be readily recycled. An especiallyappropriate polyester is polyethylene terephthalate (PET).

The spacer fabric according to the invention is characterized byimproved resistance to wear from mechanical stresses. In a preferredembodiment of the invention, the spacer fabric meets the requirements ofthe hook-and-loop fastener test according to VDA 230-210 when theexposed surface of the second knitted layer undergoes this test. Thespacer fabric meets the requirements of the hook-and-loop fastener testif the grade of 4, preferably, a grade of 5 is achieved.

Due to its resistance to wear, the spacer fabric according to theinvention can also be used as a fabric cover layer in highly stressedareas. In addition, however, the fabric has the typical elastic recoveryproperties of a spacer fabric, as well as a light, open, and breathablestructure. The overall thickness can measure, for example, between 2.5mm and 8 mm for the above applications, although this invention is notrestricted to this preferred range.

In order to achieve the densest, strongest, and most robust structurepossible, the second knitted layer can be bonded by shrinking therelevant threads at a setting temperature. Yarns are used for thispurpose that undergo noticeable shrinkage at an appropriate temperature,with the result that the stitches formed are also pulled tight. If thesecond generally planar knitted layer is provided with a perforatedstructure, this approach also yields relatively small uniform holes. Ina preferred development of the invention, the yarns for the secondknitted layer and the setting temperature are selected so that followingthe knitting process the yarns of the second knitted layer shrink atleast 5%, especially preferably, 10% due to the corresponding effect ofthe temperature.

The invention also relates to an interior furnishing, such as, forexample, a vehicle seat or the interior trim of a vehicle that includethe described spacer fabric as cover material. Other possibleapplications are, for example, the seats or the interior trim ofaircraft or rail-based vehicles such as railroads, subways, or the like.Specifically in the case of aircraft, there is a desire to use thelightest possible, most-space-saving possible seats in order to reducetotal flying weight and also to have the ability to provide sufficientspace for the greatest number of passengers. In addition, the interiorfurnishing can also relate to an item of furniture such as a chair.

The second generally planar knitted layer then provides the surface ofthe interior furnishing, that is, in particular, for the motor vehicleseat or motor vehicle interior. Due to the enhanced resistance to wear,even hook-and-loop fasteners, or other rough or sharp-edged objects arenot able to damage the interior furnishing item, or at least only ableto damage this only very little. In particular, there is no need toprovide a multilayer design in which the spacer fabric is covered by asecond cover material. Producing this type of interior furnishing, butalso the disposal and recycling of the interior furnishing is thus madeconsiderably easier. Finally, it is also possible to reduce productioncosts since there is no need to use the expensive approach of combiningdifferent materials, for which purpose an adhesive is typically used.

Due to its wear-resistant surface, the fabric according to the inventionthus provides an additional function in that the additional advantages,specifically, the elastic recovery properties and the breathability aremaintained. In particular, the invention enables the resistance to wear,the elastic properties, and the permeability to air to be adapted to andoptimized for the specific relevant specific requirements.

The following describes the invention with reference to a drawing thatshows only one illustrated embodiment. Therein:

FIG. 1 is a schematic view of a spacer fabric that includes twogenerally planar knitted layers which are attached to each other byspacer threads;

FIG. 2 shows the interlacing of the spacer threads in the firstgenerally planar knitted layer;

FIG. 3 shows the interlacing of the spacer threads in the secondgenerally planar knitted layer;

FIG. 4 is another view like FIG. 3; and

FIG. 5 is a detail of the surface of the spacer fabric at the secondgenerally planar knitted layer.

FIG. 1 provides a schematic view of a spacer fabric that includes afirst generally planar knitted layer 1 and a second generally planarknitted layer 2 that are attached to each other by spacer threads 3.FIG. 1 also clearly reveals that the second knitted layer 2 has aperforated structure with holes 4 that are covered by weft threads 5 onthe inner side, that is, the side facing the first knitted layer 1. Theexposed surface of the second knitted layer 2 is also illustrated inFIG. 5. The weft threads 5 can thus be interlaced such that they do notextend across the entire width of the second knitted layer 2 but onlyacross some of the wales. Depending on the production method, it ispossible, however, for the weft threads to be pulled completely throughtransversely, thereby producing what is known as filling.

According to the invention, the spacer threads 3 form stitches (FIG. 2)in the first knitted layer 1 by an intertwining of threads to each otherand/or to the threads of the first knitted layer 1, whereas the spacerthreads 3 on the second knitted layer 2 do not form stitches and areinterlaced there only as an inlay (FIGS. 3 and 4). This means that thespacer threads 3 on the second knitted layer 2 are held by at least oneassociated thread of the second knitted layer but forming a stitch byintertwining. For purposes of clarity, the first knitted layer 1 in FIG.2 is shown only in highly schematic fashion. Notwithstanding the highlyschematic representation, this in fact is a typical knitted layercomposed of stitches forming wales running in the production directionand stitch courses transverse thereto. For the sake of simplicity, thesewales and stitch courses are shown in FIG. 2 without reproducing theactual courses of the individual stitches of the first knitted layer 1.

A comparison of FIGS. 2 and 3 shows that the spacer threads 3 form pileloops 6 as a result of the described interlacing in the first knittedlayer 1 and the second knitted layer 2, these loops each including loopfeet created by stitches on the first knitted layer 1 and a loop head 8between the feet held on the second knitted layer 2. Although the loophead is attached to the second knitted layer 2 as a result of theinterlacing of loop head 8 as an inlay, the course of pile loop 6 isnevertheless essentially unchanged by the interlacing in the secondknitted layer 2

A critical feature of the invention is that the spacer threads 3 on thesecond knitted layer 2 run only along the inner face and are thus notaccessible from the exposed surface of the second knitted layer 2. Thespacer threads 3 on the second knitted layer 2 are thus well protectedagainst mechanical stresses caused by a hook-and-loop fastener or byother hook-like, pointed objects.

The entire spacer fabric can be composed of polyester, in particular,PET. The detail views of FIGS. 2 and 3 show that the spacer threads 3are monofilaments, whereas the first knitted layer 1 and the secondknitted layer 2 are each composed of multifilament yarns.

In the described illustrated embodiment, the second knitted layer 2includes a first stitch-forming and perforated-structure-generatingthread system 9, and a second stitch-forming thread system 10, whereinstarting from the exposed surface of the second knitted layer 2 thestitches formed by first thread system 9 are disposed on the stitchesformed by second thread system 10, and wherein the spacer threads 3 onthe second knitted layer 2 are held only by second thread system 10.

The described measures enable a spacer fabric to be provided that meetsthe requirements of the hook-and-loop fastener test according to DIN VDA230-210. The overall thickness of the spacer fabric can measure, forexample, between 2.5 mm and 8 mm.

1. In a spacer fabric comprising first and second generally planarknitted layers that are attached to each other by spacer threads, thespacer threads forming in the first knitted layer stitches by anintertwining of threads, the improvement wherein the spacer threads donot form stitches in the second generally planar knitted layer and areinterlaced there only as an inlay.
 2. The spacer fabric according toclaim 1, wherein the spacer threads form between the knitted layers pileloops on the first knitted layer that each have loop feet created bystitches and a loop head, the pile loops being held on the loop head onthe second knitted layer.
 3. The spacer fabric according to claim claim1, wherein the second knitted layer has a knit pattern comprising aperforated structure.
 4. The spacer fabric according to claim 3, whereinholes of the perforated structure are covered by weft threads on theinside of the second knitted layer.
 5. The spacer fabric according toclaim 3, wherein the second knitted layer has a first stitch-forming andperforated-structure-generating thread system, and a secondstitch-forming thread system, wherein starting from an exposed surfaceof the second knitted layer the stitches formed by the first threadsystem are disposed on the stitches formed by the second thread system,and wherein the spacer threads are held on the second knitted layer bythe second thread system.
 6. The spacer fabric according to that claim1, wherein the knitted layers and the spacer threads are composed ofpolyester.
 7. The spacer fabric according to claim 1, wherein the fabricmeets the requirements for the hook-and-loop fastener test according toVDA 230-210.
 8. The spacer fabric according to claim 1, wherein theoverall thickness measures between 2.5 mm and 8 mm.
 9. The spacer fabricaccording to that claim 1, wherein the second knitted layer is bonded byshrinking the corresponding threads at a setting temperature. 10.Interior furnishing item, in particular, motor vehicle seat or motorvehicle interior trim, characterized by a spacer fabric in the form of acover material according to claim
 1. 11. The spacer fabric according toclaim 1, wherein the knitted layers and the spacer threads are composedof PET.